Vehicular vision system with object detection

ABSTRACT

A method for detecting a vehicle via a vehicular vision system includes equipping a vehicle with a camera and providing a control at the equipped vehicle. Frames of image data captured by the camera are processed via an image processor of the control. Responsive at least in part to (i) vehicle motion information of the equipped vehicle and (ii) processing at the control of frames of image data captured by the camera, an object present in the field of view of the camera is detected and motion of the detected vehicle relative to the moving equipped vehicle is determined. The motion of the detected object relative to the moving equipped vehicle is determined by (i) determining corresponding feature points of the detected object in at least two frames of captured image data and (ii) estimating object motion trajectory of the detected object based on the determined corresponding feature points.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/899,116, filed Feb. 19, 2018, now U.S. Pat. No. 10,210,404,which is a continuation of U.S. patent application Ser. No. 15/150,843,filed May 10, 2016, now U.S. Pat. No. 9,898,671, which claims the filingbenefits of U.S. provisional application Ser. No. 62/159,515, filed May11, 2015, which is hereby incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates generally to a vehicle vision system for avehicle and, more particularly, to a vehicle vision system that utilizesone or more cameras at a vehicle.

BACKGROUND OF THE INVENTION

Use of imaging sensors in vehicle imaging systems is common and known.Examples of such known systems are described in U.S. Pat. Nos.5,949,331; 5,670,935 and/or 5,550,677, which are hereby incorporatedherein by reference in their entireties. It is known to process capturedimage data to detect objects in the field of view of the vehicle cameraor cameras. Typically, the structure of static objects is estimated viathe use of moving cameras. However, in known formulations, as soon asthe object starts to move, the estimation of the structure is typicallyerroneous and no longer valid.

SUMMARY OF THE INVENTION

The present invention provides a collision avoidance system or visionsystem or imaging system for a vehicle that utilizes one or more cameras(preferably one or more CMOS cameras) to capture image datarepresentative of images exterior of the vehicle, and provides anestimation of an object motion relative to the vehicle and camera. Themovement of the camera as the vehicle moves can be determined viavehicle movement (speed, altitude, direction, roll, pitch, yaw)information and the movement of the object is determined via themathematical model and equations of the system of the present invention.

The present invention provides for simultaneous estimation of motion andstructure of a moving object using a moving camera. The method andsystem of the present invention incorporates the estimation of themotion and structure of the unknown object into the same paradigm. Thisallows for better and more reliable estimation of the object structureas well as motion. The method and system of the present invention can beincorporated into object detection and/or three dimensional (3D)reconstruction algorithms that can benefit from the enhanced estimationof object structure and motion.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a vehicle with a vision system thatincorporates cameras in accordance with the present invention;

FIG. 2 is a perspective view of a vehicle and pedestrians forward of thevehicle and in the field of view of the forward facing camera or camerasof the vehicle;

FIG. 3 is an image of a pedestrian in front of a vehicle as may beviewed by a driver of the vehicle; and

FIG. 4 is a schematic of a moving camera and a moving object, showingwhere the moving object is imaged by the moving camera.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vehicle vision system and/or driver assist system and/or objectdetection system and/or alert system operates to capture images exteriorof the vehicle and may process the captured image data to display imagesand to detect objects at or near the vehicle and in the predicted pathof the vehicle, such as to assist a driver of the vehicle in maneuveringthe vehicle in a rearward direction. The vision system includes an imageprocessor or image processing system that is operable to receive imagedata from one or more cameras and provide an output to a display devicefor displaying images representative of the captured image data.Optionally, the vision system may provide a top down or bird's eye orsurround view display and may provide a displayed image that isrepresentative of the subject vehicle, and optionally with the displayedimage being customized to at least partially correspond to the actualsubject vehicle.

Referring now to the drawings and the illustrative embodiments depictedtherein, a vehicle 10 includes an imaging system or vision system 12that includes at least one exterior facing imaging sensor or camera,such as a rearward facing imaging sensor or camera 14 a (and the systemmay optionally include multiple exterior facing imaging sensors orcameras, such as a forwardly facing camera 14 b at the front (or at thewindshield) of the vehicle, and a sidewardly/rearwardly facing camera 14c, 14 d at respective sides of the vehicle), which captures imagesexterior of the vehicle, with the camera having a lens for focusingimages at or onto an imaging array or imaging plane or imager of thecamera (FIG. 1). Optionally, a forward viewing camera may be disposed atthe windshield of the vehicle and view through the windshield andforward of the vehicle, such as for a machine vision system (such as fortraffic sign recognition, headlamp control, pedestrian detection,collision avoidance, lane marker detection and/or the like). The visionsystem 12 includes a control or electronic control unit (ECU) orprocessor 18 that is operable to process image data captured by thecamera or cameras and may detect objects or the like and/or providedisplayed images at a display device 16 for viewing by the driver of thevehicle (although shown in FIG. 1 as being part of or incorporated in orat an interior rearview mirror assembly 20 of the vehicle, the controland/or the display device may be disposed elsewhere at or in thevehicle). The data transfer or signal communication from the camera tothe ECU may comprise any suitable data or communication link, such as avehicle network bus or the like of the equipped vehicle.

Surround awareness and driver assistance is a marketable feature forvision systems. Generic object detection using a fish eye camera is onesuch feature. Distance estimation in the scene is desired to add valueto existing detection based algorithms (such as, for example, objectdetection (OD), blind spot detection (BSD), automatic parking spotdetection or the like), and to provide a stand-alone distance estimationfeature.

Distance estimation is a triangulation-based structure from motion (SfM)problem, which requires the information on corresponding feature pointsin consecutive images and camera parameters at each viewpoint of themoving camera. A triangulation-based method can only provide areasonable solution to the application scenarios such as a movingvehicle with a stationary background and a stationary vehicle withmoving objects.

In reality, it is often required to estimate the distance of a movingobject from a moving vehicle, which leads to a challenging issue onstructure and motion estimation of a moving object using a moving camera(SaMfM). Such a structure and motion estimation of a moving object usinga moving camera (SaMfM) violates the principle of traditionaltriangulation-based solution for distance estimation. Most pastdevelopments centered around the solutions by applying differentconstraints to trajectories and velocities of the moving objects andsimultaneous estimation of moving object and moving camera.

The present invention provides a solution for structure and motionestimation of a moving object from a known moving camera. The movingcamera extrinsic parameters are retrieved from vehicle CAN messages orsignals (such as velocity and trajectory information or data). Thesystem develops solutions with respect to two different constraints ontrajectories of a rigid object, which are object translation at aconstant speed in a certain time period, and object translation at anarbitrary speed in a certain time period.

The present invention establishes a two-view constraint for motion ΔXand structure X of a moving object point:x _(t-1) ^(T) E{circumflex over (x)} _(t) =x _(t-1) ^(T) EP _(t)ΔX;  (1)where correspondent feature points x_(t-1)↔{circumflex over (x)}_(t);camera projection matrix (3×4 matrix) at t: P_(t); camera motion: R,T→3×3 essential matrix: E=[T]_(x)R

The method or system of the present invention may, in step 1, detectobject features in a captured image view, and in step 2 perform featurecorrespondence analysis between two views or feature tracking inconsecutive views, and in step 3, given a certain number ofcorrespondent feature pairs, solve equation (1) to provide an estimateof object motion ΔX. For this, an SVD method can be used. Step 4 thencalculates the structure of an object point X by using image projectionequations along with the estimated ΔX.

In the case of a 3D translation

${{\Delta\; X} = \begin{bmatrix}{\Delta\; X} \\{\Delta\; Y} \\{\Delta\; Z} \\\alpha\end{bmatrix}},$for an object of an arbitrary translation (arbitrary speed in aparticular time period), a minimum of three non-co-linear correspondingpoint pairs from two views are required to find a solution of ΔX usingequation (1) above. For an object of constant translation (constantspeed in a particular time period), only one feature object point, whichis tracked in a minimum of four views, may be required to find asolution of ΔX using equation (1).

In the case of a two dimensional (2D) translation

${{\Delta\; X} = \begin{bmatrix}{\Delta\; X} \\{\Delta\; Y} \\0 \\\alpha\end{bmatrix}},$for an object of an arbitrary translation (arbitrary speed in aparticular time period), a minimum two non-co-linear corresponding pointpairs from two views are required to find a solution of ΔX usingequation (1) above. For an object of constant translation (constantspeed in a particular time period), only one feature object point, whichis tracked in a minimum of three views, may be required to find asolution of ΔX using equation (1).

The algorithm and system and method of the present invention is operableto estimate the displacement of a rigid object in the real world fromtwo or multiple views, given that camera information at each viewpointand image corresponding points are available. In the case of a movingobject having an arbitrary translation, a minimum of three correspondingobject point pairs from two views are needed for estimation of 3D objecttranslation, while a minimum of two corresponding point pairs arerequired for 2D object displacement. In case of a moving object having aconstant translation, one feature point, tracked in a minimum of fourviews, is needed for estimation of 3D object translation, while onefeature point, tracked in a minimum of three views, is required for 2Dobject displacement.

As shown in FIG. 4, from time instant t−1 to t, the object is movingfrom position X to X+ΔX, while the camera/vehicle movement is R, T. Thecamera projection matrix is P_(t-1) and P_(t). The image featuresx_(t-1) and x_(t) are the projection of a moving object at position Xonto the camera at time instant t−1 and t, and {circumflex over (x)}_(t)is the projection of a moving object at position X+ΔX onto camera attime instant t.

From epipolar geometry (a 3×3 matrix):x _(t-1) ^(T) Ex _(t)=0  (2)

From projection geometry (a 3×4 matrix):x _(t-1) =P _(t-1) X  (3)x _(t) =P _(t) X  (4){circumflex over (x)} _(t) =P _(t)(X+ΔX)  (5)Note that x and X are the homogeneous representations of the 2D and 3Dpositions of the object.

The known information or parameters include (from vehicle CANinformation) the camera projection matrix (3×4 matrix) P_(t-1), P_(t),and camera motion (R, T↔3×3 essential matrix: E=[T]_(x)R. From featurecorresponding analysis, the corresponding point pair(x_(t-1)↔{circumflex over (x)}_(t)) is also known.

The unknown parameters to be estimated (reconstruction up to a scale)include the object position X and the object translation ΔX.

The solution involves the following steps, with Step 1 (from equations(4) and (5) above) solving the equations:{circumflex over (x)} _(t) P _(t)(X+ΔX)=x _(t) +P _(t) ΔX  (6)which results in:x _(t) ={circumflex over (x)} _(t) −P _(t) ΔX  (7)

Step 2 replaces x_(t) of equation (2) in equation (7):x _(t-1) ^(T) Ex _(t) =x _(t-1) E({circumflex over (x)} _(t) −P _(t)ΔX)=0  (8)which results in:x _(t-1) ^(T) E{circumflex over (x)} _(t) =x _(t-1) ^(T) EP _(t) ΔX  (9)Equation (9) thus provides one two-view constraint for a moving objectpoint.

Now, In the case of the 3D translation

${{\Delta\; X} = \begin{bmatrix}{\Delta\; X} \\{\Delta\; Y} \\{\Delta\; Z} \\\alpha\end{bmatrix}},$for an object of an arbitrary translation (arbitrary speed in aparticular time period), a minimum of three non-colinear correspondingpoint pairs from two views are required to find a solution of ΔX usingequation (9) above. For an object of constant translation (constantspeed in a particular time period), only one feature object point, whichis tracked in a minimum of four views, may be required to find asolution of ΔX using equation (9).

In the case of a 2D translation

${{\Delta\; X} = \begin{bmatrix}{\Delta\; X} \\{\Delta\; Y} \\0 \\\alpha\end{bmatrix}},$for an object of an arbitrary translation (arbitrary speed in aparticular time period), a minimum two non-colinear corresponding pointpairs from two views are required to find a solution of ΔX usingequation (9) above. For an object of constant translation (constantspeed in a particular time period), only one feature object point, whichis tracked in a minimum of three views, may be required to find asolution of ΔX using equation (9).

Thus, the coordinates (structure) X of a moving object point arecalculated by using equations (3) and (4) along with the estimated ΔX.

The method and system of the present invention thus may determine themotion or path of the vehicle responsive to vehicle system inputs, suchas inputs from or indicative of the vehicle steering wheel angle and/orvehicle speed and/or the like, and determines the motion and relativemotion of an object in the field of view of the camera. The system mayutilize aspects of the systems described in U.S. Patent Publication Nos.US-2014-0347486; US-2014-0350834; US-2015-0002670; US-2015-0291215;US-2015-0178576 and/or US-2015-0175072, which are hereby incorporatedherein by reference in their entireties.

The camera or sensor may comprise any suitable camera or sensor.Optionally, the camera may comprise a “smart camera” that includes theimaging sensor array and associated circuitry and image processingcircuitry and electrical connectors and the like as part of a cameramodule, such as by utilizing aspects of the vision systems described inInternational Publication Nos. WO 2013/081984 and/or WO 2013/081985,which are hereby incorporated herein by reference in their entireties.

The system includes an image processor operable to process image datacaptured by the camera or cameras, such as for detecting objects orother vehicles or pedestrians or the like in the field of view of one ormore of the cameras. For example, the image processor may comprise anEYEQ2 or EYEQ3 image processing chip available from Mobileye VisionTechnologies Ltd. of Jerusalem, Israel, and may include object detectionsoftware (such as the types described in U.S. Pat. Nos. 7,855,755;7,720,580 and/or 7,038,577, which are hereby incorporated herein byreference in their entireties), and may analyze image data to detectvehicles and/or other objects. Responsive to such image processing, andwhen an object or other vehicle is detected, the system may generate analert to the driver of the vehicle and/or may generate an overlay at thedisplayed image to highlight or enhance display of the detected objector vehicle, in order to enhance the driver's awareness of the detectedobject or vehicle or hazardous condition during a driving maneuver ofthe equipped vehicle.

The vehicle may include any type of sensor or sensors, such as imagingsensors or radar sensors or lidar sensors or ladar sensors or ultrasonicsensors or the like. The imaging sensor or camera may capture image datafor image processing and may comprise any suitable camera or sensingdevice, such as, for example, a two dimensional array of a plurality ofphotosensor elements arranged in at least 640 columns and 480 rows (atleast a 640×480 imaging array, such as a megapixel imaging array or thelike), with a respective lens focusing images onto respective portionsof the array. The photosensor array may comprise a plurality ofphotosensor elements arranged in a photosensor array having rows andcolumns. Preferably, the imaging array has at least 300,000 photosensorelements or pixels, more preferably at least 500,000 photosensorelements or pixels and more preferably at least 1 million photosensorelements or pixels. The imaging array may capture color image data, suchas via spectral filtering at the array, such as via an RGB (red, greenand blue) filter or via a red/red complement filter or such as via anRCC (red, clear, clear) filter or the like. The logic and controlcircuit of the imaging sensor may function in any known manner, and theimage processing and algorithmic processing may comprise any suitablemeans for processing the images and/or image data.

For example, the vision system and/or processing and/or camera and/orcircuitry may utilize aspects described in U.S. Pat. Nos. 8,694,224;7,005,974; 5,760,962; 5,877,897; 5,796,094; 5,949,331; 6,222,447;6,302,545; 6,396,397; 6,498,620; 6,523,964; 6,611,202; 6,201,642;6,690,268; 6,717,610; 6,757,109; 6,802,617; 6,806,452; 6,822,563;6,891,563; 6,946,978; 7,859,565; 5,550,677; 5,670,935; 6,636,258;7,145,519; 7,161,616; 7,230,640; 7,248,283; 7,295,229; 7,301,466;7,592,928; 7,881,496; 7,720,580; 7,038,577; 6,882,287; 5,929,786 and/or5,786,772, and/or International Publication Nos. WO 2011/028686; WO2010/099416; WO 2012/061567; WO 2012/068331; WO 2012/075250; WO2012/103193; WO 2012/0116043; WO 2012/0145313; WO 2012/0145501; WO2012/145818; WO 2012/145822; WO 2012/158167; WO 2012/075250; WO2012/0116043; WO 2012/0145501; WO 2012/154919; WO 2013/019707; WO2013/016409; WO 2013/019795; WO 2013/067083; WO 2013/070539; WO2013/043661; WO 2013/048994; WO 2013/063014, WO 2013/081984; WO2013/081985; WO 2013/074604; WO 2013/086249; WO 2013/103548; WO2013/109869; WO 2013/123161; WO 2013/126715; WO 2013/043661; WO2013/158592 and/or WO 2014/204794, which are all hereby incorporatedherein by reference in their entireties. The system may communicate withother communication systems via any suitable means, such as by utilizingaspects of the systems described in International Publication Nos.WO/2010/144900; WO 2013/043661 and/or WO 2013/081985, and/or U.S.Publication No. US-2012-0062743, which are hereby incorporated herein byreference in their entireties.

Optionally, the vision system may include a display for displayingimages captured by one or more of the imaging sensors for viewing by thedriver of the vehicle while the driver is normally operating thevehicle. Optionally, for example, the vision system may include a videodisplay device disposed at or in the interior rearview mirror assemblyof the vehicle, such as by utilizing aspects of the video mirror displaysystems described in U.S. Pat. No. 6,690,268 and/or U.S. Publication No.US-2012-0162427, which are hereby incorporated herein by reference intheir entireties. The video mirror display may comprise any suitabledevices and systems and optionally may utilize aspects of the compassdisplay systems described in U.S. Pat. Nos. 7,370,983; 7,329,013;7,308,341; 7,289,037; 7,249,860; 7,004,593; 4,546,551; 5,699,044;4,953,305; 5,576,687; 5,632,092; 5,677,851; 5,708,410; 5,737,226;5,802,727; 5,878,370; 6,087,953; 6,173,508; 6,222,460; 6,513,252 and/or6,642,851, and/or European patent application, published Oct. 11, 2000under Publication No. EP 0 1043566, and/or U.S. Publication No.US-2006-0061008, which are all hereby incorporated herein by referencein their entireties. Optionally, the video mirror display screen ordevice may be operable to display images captured by a rearward viewingcamera of the vehicle during a reversing maneuver of the vehicle (suchas responsive to the vehicle gear actuator being placed in a reversegear position or the like) to assist the driver in backing up thevehicle, and optionally may be operable to display the compass headingor directional heading character or icon when the vehicle is notundertaking a reversing maneuver, such as when the vehicle is beingdriven in a forward direction along a road (such as by utilizing aspectsof the display system described in International Publication No. WO2012/051500, which is hereby incorporated herein by reference in itsentirety).

Optionally, the vision system (utilizing the forward facing camera and arearward facing camera and other cameras disposed at the vehicle withexterior fields of view) may be part of or may provide a display of atop-down view or birds-eye view system of the vehicle or a surround viewat the vehicle, such as by utilizing aspects of the vision systemsdescribed in International Publication Nos. WO 2010/099416; WO2011/028686; WO 2012/075250; WO 2013/019795; WO 2012/075250; WO2012/145822; WO 2013/081985; WO 2013/086249 and/or WO 2013/109869,and/or U.S. Publication No. US-2012-0162427, which are herebyincorporated herein by reference in their entireties.

Changes and modifications in the specifically described embodiments canbe carried out without departing from the principles of the invention,which is intended to be limited only by the scope of the appendedclaims, as interpreted according to the principles of patent lawincluding the doctrine of equivalents.

The invention claimed is:
 1. A method for object detection using avehicular vision system, said method comprising: equipping a vehiclewith a camera so that the camera is disposed at an in-cabin side of awindshield of the equipped vehicle and has a field of view forward ofthe equipped vehicle through the windshield; providing a control at theequipped vehicle, the control comprising an image processor; capturingframes of image data with the camera; processing at the control framesof image data captured by the camera; providing to the control vehiclemotion information of the equipped vehicle; wherein the provided vehiclemotion information includes at least speed of the equipped vehicle andtrajectory of the equipped vehicle; while the equipped vehicle ismoving, and responsive at least in part to (i) processing at the controlof vehicle motion information of the equipped vehicle and (ii)processing at the control of frames of image data captured by thecamera, detecting an object present in the field of view of the cameraand determining motion of the detected object relative to the movingequipped vehicle; and wherein determining motion of the detected objectrelative to the moving equipped vehicle comprises (i) determiningcorresponding feature points of the detected object in at least twoframes of image data captured by the camera and (ii) estimating objectmotion trajectory of the detected object based on the determinedcorresponding feature points.
 2. The method of claim 1, whereindetermining motion of the detected object relative to the movingequipped vehicle is responsive at least in part to utilization of atleast two constraints on trajectory.
 3. The method of claim 2, whereinthe at least two constraints comprise (i) object translation at aconstant speed over a certain time period and (ii) object translation atan arbitrary speed over a certain time period.
 4. The method of claim 1,wherein providing to the control vehicle motion information comprisesproviding to the control vehicle motion information via a communicationbus of the equipped vehicle.
 5. The method of claim 4, wherein thecommunication bus comprises a CAN bus of the equipped vehicle.
 6. Themethod of claim 1, comprising providing a display at the equippedvehicle for viewing by a driver of the equipped vehicle, and displayingvia the display images derived from image data captured by at least somecameras of a multi-camera surround view vision system of the equippedvehicle to assist the driver in maneuvering the equipped vehicle.
 7. Themethod of claim 1, wherein the camera comprises an imager having atleast one million photosensing elements arranged in rows and columns. 8.The method of claim 1, wherein the provided vehicle motion informationincludes steering angle of the equipped vehicle.
 9. The method of claim1, wherein the detected object is a pedestrian.
 10. The method of claim9, wherein the camera is part of a pedestrian detection system of theequipped vehicle.
 11. The method of claim 1, wherein the detected objectis another vehicle.
 12. The method of claim 11, wherein the camera ispart of a collision avoidance system of the equipped vehicle.
 13. Themethod of claim 1, comprising determining structure of the detectedobject based on the estimated object motion trajectory of the detectedobject.
 14. The method of claim 1, wherein moving feature points aredetermined via the following equation:x _(t-1) ^(T) E{circumflex over (x)} _(t) =x _(t-1) ^(T) EP _(t) ΔX;where x_(t-1) and x_(t) are projections at position X at time instantst−1 and t, {circumflex over (x)}_(t) is projection at position X+ΔX attime instant t, and P_(t) is a projection matrix of the camera.
 15. Themethod of claim 14, comprising performing a feature correspondenceanalysis between two frames of captured image data and, given a numberof correspondent feature pairs, solving the equation to provide anestimate of object motion ΔX.
 16. The method of claim 15, comprisingcalculating structure of an object point X by using image projectionequations along with the estimated object motion ΔX.
 17. A method forobject detection using a vehicular vision system, said methodcomprising: equipping a vehicle with a camera so that the camera isdisposed at an in-cabin side of a windshield of the equipped vehicle andhas a field of view forward of the equipped vehicle through thewindshield; wherein the camera comprises an imager having at least onemillion photosensing elements arranged in rows and columns; wherein thecamera is part of a pedestrian detection system of the equipped vehicle;providing a control at the equipped vehicle, the control comprising animage processor; capturing frames of image data with the camera;processing at the control frames of image data captured by the camera;providing to the control vehicle motion information of the equippedvehicle; wherein providing to the control vehicle motion informationcomprises providing to the control vehicle motion information via acommunication bus of the equipped vehicle; wherein the provided vehiclemotion information includes at least speed of the equipped vehicle andtrajectory of the equipped vehicle; while the equipped vehicle ismoving, and responsive at least in part to (i) processing at the controlof vehicle motion information of the equipped vehicle and (ii)processing at the control of frames of image data captured by thecamera, detecting a pedestrian present in the field of view of thecamera and determining motion of the detected pedestrian relative to themoving equipped vehicle; and wherein determining motion of the detectedpedestrian relative to the moving equipped vehicle comprises (i)determining corresponding feature points of the detected pedestrian inat least two frames of image data captured by the camera and (ii)estimating pedestrian motion trajectory of the detected pedestrian basedon the determined corresponding feature points.
 18. The method of claim17, wherein the communication bus comprises a CAN bus of the equippedvehicle.
 19. The method of claim 17, comprising providing a display atthe equipped vehicle for viewing by a driver of the equipped vehicle,and displaying via the display images derived from image data capturedby at least some cameras of a multi-camera surround view vision systemof the equipped vehicle to assist the driver in maneuvering the equippedvehicle.
 20. The method of claim 17, wherein the provided vehicle motioninformation includes steering angle of the equipped vehicle.
 21. Amethod for object detection using a vehicular vision system, said methodcomprising: equipping a vehicle with a camera so that the camera isdisposed at an in-cabin side of a windshield of the equipped vehicle andhas a field of view forward of the equipped vehicle through thewindshield; wherein the camera comprises an imager having at least onemillion photosensing elements arranged in rows and columns; providing acontrol at the equipped vehicle, the control comprising an imageprocessor; capturing frames of image data with the camera; processing atthe control frames of image data captured by the camera; providing tothe control vehicle motion information of the equipped vehicle; whereinthe provided vehicle motion information includes at least speed of theequipped vehicle and trajectory of the equipped vehicle; while theequipped vehicle is moving, and responsive at least in part to (i)processing at the control of vehicle motion information of the equippedvehicle and (ii) processing at the control of frames of image datacaptured by the camera, detecting an object present in the field of viewof the camera and determining motion of the detected object relative tothe moving equipped vehicle; wherein determining motion of the detectedobject relative to the moving equipped vehicle comprises (i) determiningcorresponding feature points of the detected object in at least twoframes of image data captured by the camera and (ii) estimating objectmotion trajectory of the detected object based on the determinedcorresponding feature points; and determining structure of the detectedobject based on the estimated object motion trajectory of the detectedobject.
 22. The method of claim 21, wherein the detected object isanother vehicle.
 23. The method of claim 22, wherein the camera is partof a collision avoidance system of the equipped vehicle.
 24. The methodof claim 22, wherein providing to the control vehicle motion informationcomprises providing to the control vehicle motion information via acommunication bus of the equipped vehicle.
 25. The method of claim 22,wherein the provided vehicle motion information includes steering angleof the equipped vehicle.